Pad printing is a conventional process in which a printing blanket (i.e., a printing pad) is pressed against a printing original plate (i.e., an image plate), on which ink is disposed in accordance with a printing pattern, so as to transfer (pick up) the ink from the printing original plate, and then the printing blanket is pressed against a to-be-printed surface so as to transfer (deliver) the ink to a to-be-printed surface, whereby the printing pattern is printed onto the to-be-printed surface. There is disclosed an invention in which, in order to prevent reduction in the printing quality, a printing original plate is reciprocally moved so as to shake and stir ink in an ink box that is in contact with the printing original plate and thereby make the ink less likely to be cured (see Patent Literature 1, for example).